At least three electrically conducting blocks are disposed within an isolating region; and at least two of them are mutually separated and capacitively coupled by a part of the isolating region. At least two of them, being semiconductor, have opposite types of conductivity or identical types of conductivity, but with different concentrations of dopants, and these are in mutual contact by one of their sides. The mutual arrangement of these blocks within the isolating region, their type of conductivity and their concentration of dopants form at least one electronic module. Some of the blocks define input and output blocks.
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6. An electronic device comprising:
a substrate; and
a plurality of logic circuits in said substrate, each logic circuit comprising
an isolating region,
a first resistor block,
a second resistor block, and
a control block being laterally spaced apart from and laterally outside of said first and second resistor blocks and being capacitively coupled by a part of the isolating region to said first and second resistor blocks,
said control, and first and second resistor blocks each having coplanar lowermost planar surfaces and coplanar uppermost planar surfaces,
at least two of the control, and first and second resistor blocks having different semiconductor properties and being in mutual contact by one of their sides, the different semiconductor properties comprising at least one of different conductivity types or different dopant concentrations.
10. An electronic device comprising:
a substrate; and
a plurality of inverters in said substrate, each inverter comprising
an isolating region,
a drain block,
a source block,
a channel block between said drain and source blocks, and
a gate block being laterally spaced apart from and laterally outside of said drain, channel, and source blocks and being capacitively coupled by a part of the isolating region to said drain, channel, and source blocks,
said gate, drain, channel, and source blocks each having coplanar lowermost planar surfaces and coplanar uppermost planar surfaces,
at least two of the drain, channel, and source blocks having different semiconductor properties and being in mutual contact by one of their sides, the different semiconductor properties comprising at least one of different conductivity types or different dopant concentrations.
1. An electronic device comprising:
a substrate; and
a plurality of transistors in said substrate, each transistor comprising
an isolating region,
a drain block,
a source block,
a channel block between said drain and source blocks, and
a gate block being laterally spaced apart from and laterally outside of said drain, channel, and source blocks and being capacitively coupled by a part of the isolating region to said drain, channel, and source blocks,
said gate, drain, channel, and source blocks each having coplanar lowermost planar surfaces and coplanar uppermost planar surfaces,
at least two of the drain, channel, and source blocks having different semiconductor properties and being in mutual contact by one of their sides, the different semiconductor properties comprising at least one of different conductivity types or different dopant concentrations.
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The invention relates to microelectronics, and more particularly, to the processing of electronic information, such as electrical signals (current and/or voltage) using a mutual arrangement of electrically conducting, for example, semiconducting, blocks, particularly active-zone blocks.
Transistors are widely used in electronic devices. A typical transistor includes spaced apart source and drain regions with a channel extending therebetween. A gate structure, including a gate dielectric and gate conductor, is typically formed over the channel. A conventional structure of such a transistor may include a sometimes complex stack of semiconducting and/or metallic zones.
Such conventional transistor are also commonly arranged to define logic circuits, such as for Boolean operations, that may also be relatively complicated to form.
According to one mode of implementation and embodiment, it is proposed to produce an electronic device by using “elementary bricks” formed of electrically conducting blocks, for example, semiconducting and/or metallic blocks, mutually arranged to form one or more electronic modules, such as, for example, one or more MOS transistors. The arrangement of the blocks forming the module depend on the electronic function desired for the module. It is possible to form in an extremely flexible manner any electronic device carrying out an electronic function, and particularly transistors, while avoiding the conventional structure of a transistor using a sometimes complex stack of semiconducting and/or metallic zones.
It may also become possible to produce logic circuits, for example, Boolean operators, in an extremely simple manner without using conventional transistor structures.
According to one aspect, there is proposed an electronic device production method comprising a formation within an isolating region of at least three electrically conducting blocks. At least two blocks, for example semiconducting and/or metallic, are mutually separated and in mutual capacitive coupling by way of a part of the isolating region and at least two semiconducting blocks exhibiting opposite types of conductivity or identical types of conductivity, but with different concentrations of dopants, are in mutual contact by one of their sides. The choice of the number of blocks, of their type of conductivity, of their concentration of dopants and their mutual arrangement make it possible to form at least one electronic module having at least one desired electronic function.
The method also comprises a selection of at least two blocks from among those forming the at least one electronic module intended to have electrical signals be applied, a selection of at least one block from among those forming the at least one electronic module intended to deliver an electrical signal in response to the signals applied. The selection of these blocks depending on the at least one electronic function of the at least one electronic module.
Thus, according to one mode of implementation, the electronic function of the module thus produced is obtained solely by capacitive coupling between certain electrically conducting blocks, for example, semiconducting and/or metallic blocks, and by contact between other semiconducting blocks.
It then becomes possible to form, for example, the blocks of at least one module, for example a MOS transistor, and optionally the blocks of several modules or indeed of all the modules, in one and the same plane or same level, so as to produce a module, or indeed a part or the entirety of a device, having an essentially two-dimensional structure. This is therefore distinguished from the conventional structure of a MOS transistor comprising an insulated gate above the source, drain and channel active zones.
Blocks extending in one and the same plane (horizontal, vertical or oblique) or coplanar blocks, are understood in particular as being blocks all possessing at least one face, the at least one face of all these blocks being all coplanar. That is to say all extending in one and the same plane. These coplanar faces may be, for example, the upper faces of the blocks and the heights of the blocks may be identical (in this case the lower faces of the blocks are also coplanar) or different.
It is also possible to form blocks of a first module in a first plane and the blocks of a second module in a second plane different from the first so as to produce a device of three-dimensional structure. Thus, for example, it is possible to stack levels of blocks to produce a plurality of electronic modules in an extremely simple manner.
When several electronic modules are formed, it is possible, according to one mode of implementation, to produce an electrical coupling between the electronic modules by way of at least one of their respective blocks, for example, by using metallizations or metal lines. These may be customarily used in the interconnections (Back End Of Lines: BEOL according to a term well known to the person skilled in the art) of an integrated circuit, or else, for example, by electrically conducting trenches may also be used, for example, those filled with metal, which may or may not be coplanar with the blocks.
So as to favor an electrically conducting contact tap on at least some of the selected blocks, such as semiconducting blocks, and having to receive or deliver electrical signals, it may be particularly advantageous to carry out on these blocks a post treatment, for example a silicidation, especially if these blocks are made of silicon.
Any semiconducting material is suitable for the production of at least some of the blocks of an electronic device such as described herein. It is for example possible to use a conventional semiconducting material such as silicon, polysilicon or Group III-V materials. That said, it would also be possible to use carbon.
Likewise, any insulating material forming the isolating region is suitable. It is possible to use insulating or dielectric materials such as silicon dioxide, but also a material such as glass, or else a flexible or rigid, polymer and/or organic insulating material.
According to one embodiment, at least some of the blocks are formed within an isolating region made in a semiconductor substrate, such as an integrated circuit conventional substrate.
The blocks may be formed of a semiconductor material of monocrystalline or polycrystalline structure, for example, silicon or polysilicon and, for example, of the same material as that of the semiconductor substrate in which the isolating region is produced.
It is then possible to form at least one part of the isolating region with trenches containing a field oxide. This field oxide, typically silicon dioxide, is for example analogous to that formed in shallow isolation trenches, known by the person skilled in the art by the name STI: Shallow Trench Isolation.
Thus, when producing a MOS transistor, the block forming the gate of the transistor, which is in capacitive coupling with the block forming the channel region, is separated from this channel region by a field oxide and not by a conventional gate oxide. This simplifies production and furthermore makes it possible to modulate the threshold voltage of the transistor by simply altering the distance separating the block forming the gate of the MOS transistor and the block forming the channel region. This is not possible at present since for a given technology, since the gate oxide of a transistor has a determined and fixed thickness.
Although it is possible to use a bulk substrate as semiconductor substrate, it is particularly advantageous to use an SOI substrate (SOI: Silicon On Insulator according to a term well known to the person skilled in the art). In this case, at least one part of the isolating region is made within the upper semiconductor layer of the substrate of SOI type. The buried insulating layer of the substrate can then advantageously be used to form another part of the isolating region, typically the lower part.
According to another aspect, there is proposed an electronic device, comprising at least three electrically conducting blocks disposed within an isolating region; at least two of them, for example, semiconductor and/or metallic, are mutually separated and capacitively coupled by way of a part of the isolating region and at least two of them are semiconductor and exhibit opposite types of conductivity or identical types of conductivity but with different concentrations of dopants and are in mutual contact by one of their sides. The mutual arrangement of these blocks within the isolating region, their type of conductivity and their concentration of dopants forming at least one electronic module having at least one desired electronic function. At least two blocks from among those forming the at least one module are intended to have electrical signals be applied, and at least one block from among those forming the at least one module are intended to deliver an electrical signal in response to these signals applied having regard to the at least one electronic function. According to one embodiment, the blocks intended to have electrical signals be applied and the block or blocks intended to deliver one or more electrical signals comprise electrical contact tap zones.
According to one embodiment, the device comprises several electronic modules electrically coupled by way of at least one of their respective blocks.
At least some of the blocks may be situated within an isolating region made in a semiconductor substrate, the blocks possibly being formed of a semiconductor material of monocrystalline or polycrystalline structure and at least one part of the isolating region can comprise trenches containing a field oxide.
The semiconductor substrate used may be a substrate of the SOI type.
According to one embodiment, the blocks of at least one module extend in one and the same plane so as to produce a module of essentially two-dimensional structure.
It is also possible for the blocks of each module to extend in one and the same plane. As a variant, the blocks of at least one first module extend in a first plane and the blocks of at least one second module extend in a second plane different from the first so as to produce a device of three-dimensional structure.
At least one electronic module can comprise at least one of a transistor, a logic circuit, a resistor of controllable resistive value, a controllable PN junction, an inverter, and a memory cell. For all these elements, the blocks forming the element may be coplanar.
According to one embodiment, the element comprises at least one first block in capacitive coupling with at least one other block by way of a part of the isolating region, the at least one first block forming a control electrode for the element.
Other advantages and characteristics of the invention will be apparent on examining the detailed description of wholly non-limiting modes of implementation and embodiments, and the appended drawings in which:
In
At least two blocks from among those forming the electronic module are selected (step 140) so as to form input blocks intended to have electrical signals applied thereto. At least one output block intended to deliver an electrical signal in response to the signals applied is also selected (step 15). The selection of these blocks also depends on the electronic function of the electronic module MDL. The method also includes a post treatment (steps 16, 17) on at least one selected block.
And, although not indispensable, it may however be desirable to perform a post-treatment on the selected input and output blocks so as to favor an electrical contact tap on these blocks, in particular, in the case of a contact tap in the plane or perpendicular to the latter. Such a post-treatment may be for example a conventional silicidation treatment.
In fact, as seen in
An electronic module may be a component such as a transistor, a resistor of controllable or fixed resistive value, a capacitor, a controllable PN junction, or else a logic circuit, for example, implementing a Boolean operator (OR, AND, EXCLUSIVE OR etc. logic function) or an inverter, or a memory cell, without this list being exhaustive.
The device DIS comprises several semiconductor blocks which may be of conductivity type N or of conductivity type P with different concentrations of dopants. The blocks of the device are in this example situated in one and the same plane, that is to say they each exhibit at least one face, for example their upper face, all these faces being coplanar.
In
Such blocks form for example modules MDL20 and MDL21 which are respectively PMOS and NMOS transistors. Other blocks are in mutual capacitive coupling by way of a part of the isolating region RIS. Of course, the distance d between capacitive blocks in mutual coupling will condition the capacitive value of the coupling. The lower the distance the higher the capacitive value will be and the higher the distance the lower the capacitive value will be.
The person skilled in the art will know how to choose the distance separating two blocks in capacitive coupling as a function of the desired coupling. By way of example, when the isolating region is a field oxide, for example, of the type of that used in shallow isolation trenches (STI), a distance of between 0 and 500 nanometers, for example 55 nanometers, will be chosen.
It is also noted in the device DIS that the block EC forms a control electrode for the two transistors MDL20 and MDL21. The whole assembly then forms a module MDL2 which is in fact an inverter.
The inverter MDL2 here forms an output stage for the device PIS and, the latter also comprises other blocks situated upstream of this output stage 1. These other blocks form another module MDL1 which is, for example, a logic circuit. Therefore, the device here comprises a processing stage followed by an output stage. The device also comprises two input blocks BLCPA and BLCPB intended to receive two input voltages Va and Vb. It also comprises two output blocks BLCPS and BLCPNS mutually linked by a metallization MTL and intended to deliver an output voltage Vs.
Other blocks are linked to the supply voltage Vdd by way of one metallization MTL and other blocks are grounded GND by way of other metallizations MTL. These metallizations comprise, for example, metallic tracks and vias of the type of those present in the back end of line (BEOL) part of an integrated circuit.
As a variant it would be possible to replace at least one of these metallizations by at least one electrically conducting trench extending in the isolating region RIS in a coplanar or non-coplanar manner with the various blocks. The trench or trenches may be, for example, filled with a metal.
Although the region RIS may be produced within a substrate SUB of bulk type, it may be particularly advantageous, as illustrated in
The device DIS is then, for example, as illustrated in
The blocks BLC are isolated at the bottom by way of the buried oxide BX and for those which are in capacitive coupling, isolated by isolating trenches TIS, for example, shallow isolation trenches STI optionally of different depths. These trenches are conventionally filled with a field oxide, for example, silicon dioxide. These trenches and their filling are produced in a conventional manner known in the field of integrated circuit fabrication.
As a variant, as illustrated in
Another isolating region RIS2 is deposited above the region RIS1 and incorporates blocks BLC2 forming one or more other modules of the device DIS.
Here again, the blocks BLC2 extend in another plane XY parallel to the module BLC1 but at a higher level. Of course, it would also be possible that a module MDL of the device DIS can be formed by a block BLC1 situated in the isolating region RIS1 and by one or more blocks BLC2 situated in the region RIS2. Thus, a module of the device DIS can extend in a plane YZ.
For the sake of simplification of
Reference is now made to
In
The block BLCP1 is also of conductivity type P with a P+ doping. That said, it would be possible to use a block of any other type of conductivity and/or of doping, for example, a doping of type “P intrinsic” (Pint), exhibiting a lower doping P than the doping P+, for example 1014 atoms/cm3.
The block BLCP3 of conductivity type P with a P+ doping is distant from the block BLCP2 and is capacitively coupled with the latter so as to form a capacitor as illustrated in
The block BLCN is intended to receive the supply voltage Vdd while the block BLC3 is intended to be grounded GND. The block BLCP1, forming the control electrode, is intended to receive a control voltage Va while the block BLC2 is intended to form the output node of the memory cell and to deliver an output voltage Vs.
When the control voltage Va is zero, or lower than the threshold voltage of the diode, the voltage Vs is zero since the diode is disabled and the capacitor is grounded.
On the other hand, when the control voltage Va becomes greater than the threshold voltage of the PN junction, the capacitive coupling then brings about the creation of an inversion channel of the junction, the effect of which is to cause the voltage Vs to rise to a value Vdd1 lower than the value Vdd and charging the capacitor. And, this voltage will thereafter decrease by recombination of the carriers in the PN junction until it regains the zero value. A memory cell has therefore indeed been produced.
It is also possible to produce a memory cell by using the module illustrated in
Moreover, the block BLCP2 is a block of type “P intrinsic” (Pint), exhibiting a lower P doping than the P+ doping, for example, 1014 atoms/cm3. The other blocks are similar to those which were described with reference to
It is therefore seen that the blocks BLCP4 and BLCP2 form a resistor of variable resistive value, with the control electrode EC (block BLCP1) making it possible to control the resistive value of this resistor. More precisely, the module BLCP2 (Pint) exhibits a quasi-infinite resistance while the block BLCP4 (P+doped) exhibits a lower resistive value.
Moreover, the capacitive coupling between the block BLCP1 and the blocks BLCP4 and BLCP2 is likened to a MOS effect. Therefore, when the voltage Va is zero, the resistive value between the node Vdd and the output node Vs is quasi-infinite on account of the presence of the block BLCP2 having the intrinsic P doping. On the other hand, when the voltage Va is greater than the threshold voltage of the “MOS transistor”, an inversion channel is then created along the variable resistance which results in a charge carrier intake. Consequently, the doping of the block BLCP2 increases and the resistance decreases. Therefore, the voltage Vs increases to attain a voltage Vdd2 lower than the voltage Vdd.
When the voltage Va drops back to zero, there is again a recombination of carriers between the blocks BLCP2 and BLCP4 causing the output voltage Vs to drop back to zero.
Here again therefore a memory cell has been created, with the aid of a resistor of controllable variable resistive value. That said, such a structure may exhibit less leakage than that illustrated in
Here, the control electrode BLCP1 was P+ doped. That said, it would be possible to take a block BLCP1 N+ doped or else having a doping of the intrinsic P type that is to say a lower doping than the P+ doping. The choice of the type of conductivity and of the concentration of dopants makes it possible to condition the threshold voltage of the module.
More precisely, the threshold voltage VT of the structure BLCP1, BLCP2, BLCP4 is given by the following formula:
with
where
The module MDL illustrated in
More precisely, the block BLCP40 (P+ doped) and the block BLCP20 (intrinsic P doped) together with the control electrode EC1 form a first resistor of resistive value controllable by the voltage Va (“Set”). Moreover, the blocks BLCP41 and BLCP21 are respectively analogous to the blocks BLCP40 and BLCP20. They form with the second control electrode EC2 a second resistor of resistive value controllable by the voltage Vb (“Reset”).
The two blocks BLCP20 and BLCP41 are in mutual contact by one of their sides and the output node Vs is taken on the block BLCP20.
When the voltage Va becomes greater than the threshold voltage, the voltage Vs rises until it attains a value Vdd2 that is lower than the voltage Vdd. And, if it is desired to reinitialize the memory cell, a voltage Vb greater than the threshold voltage is then applied, the effect of which is then to cause the voltage Vs to drop back much more rapidly to ground.
Moreover, a block BLCP1 P+ doped, is in capacitive coupling with the previously mentioned blocks, and in particular with the block BLCP2. The block BLCP1 forms the gate of the transistor, the blocks BLCN1 and BLCN2 form the two conduction electrodes of the transistor (drain and source), it being understood, of course, that the drain and source of the transistor are interchangeable with regard to the symmetry of the structure. Finally, the block BLCP2 forms the channel of the transistor.
The part OX of the isolating region situated between the block BLCP1 and the blocks BLCN1, BLCP2 and BLCN2 forms the gate oxide of the transistor.
It should be noted, as illustrated in the
It will be noted that the transistor thus produced comprises blocks situated in one and the same plane (on one and the same level), the gate of the transistor not being above the channel region, but at the same level as this channel region and laterally disposed therefrom. The thickness of the region OX makes it possible to modulate the threshold voltage of the transistor.
Measurements of drain/source current Ids as a function of the voltage Vgs and of the voltage Vds have been performed on the device of
The change of the current Ids as a function of the voltage Vgs (curve CV1) shows that such a transistor exhibits a high threshold voltage equal to 5 volts (
For this reason and to avoid overly large leakage, the PMOS transistor comprises for the channel region, a block BLCP3 P doped with a doping of intrinsic P type (for example 1014 atoms/cm3). The module MDL also comprises on either side of this module BLCP3, and in contact with the latter, two blocks BLCP2 and BLCP4 P+ doped (typically 1020 atoms/cm3) and forming the drain and source regions, it being understood, of course, that here again the drain and source regions are interchangeable.
Moreover, in
The PMOS transistor of
If the gate voltage Va is zero, then the channel region exhibits an infinite resistance while in the presence of a voltage Va greater than the threshold voltage, there is accumulation of carriers in the channel zone and the doping of the latter passes from a doping of the intrinsic P type to a doping of the P+ type.
The topology of this transistor is, for example, identical to that which was illustrated in
In
The module MDL therefore forms a coplanar inverter based on complementary transistors. In the example described here this inverter is also assumed to be produced in a substrate of the SOI type, in particular, of the fully depleted type since the PMOS transistor (MDLA) comprises resistors of variable resistive values.
In
Indeed, if the voltage Va is zero, the output is zero whatever the value of Vb. If the voltage Vb is zero, the output Vs is zero whatever the value of Va. And, if both the voltages Va and Vb have the logic value “1” (application of Vdd to both inputs), then the voltage Vs passes to “1” through the creation of inversion channel along the diode or the variable resistor.
Although described hereinabove is the possibility of producing a memory cell, for example, by replacing the diode of a memory cell by a MOS transistor of P or N type.
By way of example the MOS transistor of
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